"I have been authenticated to use an oracle database(11g). I'm provided with the DNS Name and TNS service name. This helps me in connecting via AQT tool, but I want to interface it to my DAO. Will anyone please help me to connect it using jdbc."

The port is always going to be the same unless some non-default setup was
done. The DNS name is probably the name of the server. Ping it to see
what the IP address is. The listener name is probably the SID.

Look in your tnsnames.ora file. All that information will be in there.
You have access to one since you are already connecting to the db with
another tool unless that tool is using JDBC. Then it will be in a config
file somewhere.

Connecting Oracle using JDBC
You need to download ojdbc14.jar.
and paste it into the folder where your jdbc program resides.
Then follow the below steps.... so that your database connects to java using jdbc.

There are 4 drivers for JDBC.
The best suitable for Java is Type-IV driver, which is also called Thin Driver.
You can simply copy & paste code given below for connecting jdbc with oracle.
Class.forName(""oracle.jdbc.OracleDriver"");
Connection con = DriverManager.getConnection(""jdbc:oracle:thin:@localhost:1521:xe"",""system"",""manager"");